A fluidized bed heater consists of a container or housing (mantle) in which a bed of particulate or granular material is placed upon a distribution plate or diffuser. A gas (typically inert) is supplied to a manifold under the distribution plate, which serves to evenly distribute the gas under the plate. The gas penetrates through openings in the distribution plate, passes upward through the bed of granular or particulate material, and finally is exhausted from the heater after clearing the bed.
As the gas flow rate increases through the bed, bed particles, due to drag forces which counteract the force of gravity, begin to lift upwards and the bed exhibits the appearance of a viscus fluid. Thus the bed is said to be fluidized. Heat may be supplied to or removed from the bed by heating or cooling the gas which passes through the bed or by heating or cooling wires or tubes situated in the bed of granular material. Fluidized bed heaters have been used in several industrial processes. For example, U.S. Pat. No. 4,190,235, issued to Dell on Feb. 26, 1980, which is incorporated herein by reference, describes a high-temperature, fluidized bed for sustaining temperatures of at least 2000.degree. C. for heating ladles of the type commonly used in the foundry and steel industry prior to their receiving a charge of molten metal.
Fluidized heaters have also been used in the oil industry. For example, U.S. Pat. No. 4,338,887, issued to Leon on July 13, 1982, which is incorporated herein by reference, describes a low-profile, fluid-bed heater for the steam-flooding process of oil recovery.